Punctureproof tube for tires



' ma. 24, 1940. C, VRETMAN 2,226,453

PUNCTUREFROOF TUBE FOR TIRES Filed Nov. 19, 1938 Caml Wefzzafz) Patented Dec. 24, 1940 UNITED STATES PATENT OFFICE 2,226,453 PUNoTUnEPRooF TUBE Fon TIRES Carl G. VretmarnAtlanta,` Ga. Application November 19, 1938, serial No. 241,415

claims. (C1. 152-359)v My invention relates to improvements in punctureproof tubes for tires. y

The object of my invention is to provide an inner tube having an auxiliary air space arranged 5` circumferentially around its outer wall and so constructed, that in the event the same is punctured, the pressure in the main air space will force the outer Wall thereof into the auxiliary air space and form a completely inated tire of slightly less pressure.

Another object of my invention is to provide a tube of this character in which the auxiliary air space may be supplied with comparatively low initial inflation before the tube is placed in the casing. The subsequent placing of the tube in the casing and inflation of the main air space, after having reached the same pressure as that of the initial previously inflated auxiliary air space will then be the same on each side of the partition until full inflation is accomplished.

A further object of my invention is to provide means within the auxiliary air space to prevent nails or the like, which may enter the same, from passing through the wall between the auxiliary 2 and main air spaces and thus prevent the puncturing of the main air space.

A still further object of my invention is to provide a tube of this character which may be used on any standard make of casing, and at the same time providing a simple construction, with safety in operation, and having certaindetails of structure and operation hereinafter more fully set forth.

In the drawing- Figure 1 is a transverse sectional view of my improved tubeshowing the auxiliary air space inated;

Figure 2 is a transverse sectional view of a` casing--showing my tube therein and the tube fully inflated, and the tire ready for use;

Figure 3 is a transverse sectional view similar to Figure 2-showing the auxiliary space deflated after a puncture and the Wall of the main air space forced into the same;

Figure 4 is a longitudinal sectional view taken on the line 4--4 of Figure 1;

Figure 5 is a transverse section of a modified form of tube;

50 Figure 6 'is a transverse sectional View of the form of tube shown in Figure 5--showing the auxiliary air space deflated after a puncture.-

It is well known that most tire trouble is caused by nailsV or the like entering the outer casing of 55 the tire sufficiently far to puncture the inner tube and is then thrown from the tire by centrifugal force or lthe working of the tire. In my improved tube the auxiliary air space only is punctured and the nail or the like is thrown from the tire before it can enter the wall between the air spaces.

Referring now to the drawing, I represents the ordinary inner tube; but, as shown in my inven.- tion, the outer portion thereof which abuts the tread of the outer casing 2, is thickened, as in- 10 dicated at 3, for a purpose hereinafter more fully described. The tube I, at its inner periphery, is provided with the usual valve stem and valve 4, by means of which the tube is inflated in the usual manner and needs no further description.

The tubev I, adjacent its upper thickened portion 3, is provided with a partition 5, as shown in Figure 1 of the drawing, which divides the tube into an auxiliary air space I0 and a main air 20 space I I. The outer thickened wall 3 of the tube is provided with an elongated recessed portion 6, having vertical end walls 'I and 8. Secured within the end Wall 1 of the recess is a valve stern 9 which carries an inflating valve, and said valve 25 stem lies longitudinally in the recess when the tube is in the casing. By this arrangement it will be seen that the auxiliary air space I0 is inflated through the valve stem 9, while the main air space II is inflated through the valve stem 4. 3o

The wall 3, as heretofore stated, is thickened and must be sufciently thick so as not to expand when the space I0 is inflated to approximately ten pounds pressure. The wall 5, however, must V be of less thickness to take up the expansion, 35 but must be thick enough so that the space IB will not be too large to be inserted into the tire casing. W'hile inflating the outer auxiliary space I0 it might be necessary to keep the valve 4 open so that the space II will not be expanded, and 40 thus allow the ready insertion of the tube in the tire casing.

In the use of the tube the auxiliary air space I0 is inflated through the valve stem 9 until a pressure of approximately ten pounds is obtained therein, which causes the partition 5 to assume the position shown in Figure 1 of the drawing. After its insertion in the casing the main air space II is then inflated to the desired number of pounds of pressure. This pressure causes the partition 5 to be forced outwardly resulting in an increased pressure in the auxiliary space IB until the partition has reached a point of approxi- `mately that shown in Figure 2-When the pres- 55 sure in both the main and the auxiliary spaces are equal.

In order to prevent the lower wall of the recessed portion 6 from being expanded outwardly against the metal valve stem 9, I provide a rubber sleeve I3 which is of a size to approximately ll the recessed portion 6.

Should a nail or the like pass through the casing and puncture the outer Wall of the outer or auxiliary space Ill, and then by centrifugal force be thrown or in some way worked out `,of the tire, the wall 5, by the air pressure in the main air space Il, would then be forced outwardly in the position shown in Figure 3, and the entire tire would still be inated with a slightly less pressure. The expansion of space Il willtake place with the sarne speed and proportion as the deation or collapse of space I0, so that the actual fact a puncture has taken place will not be noticeable to the occupants of a car.

In the modification shown in Figure the wall of the outer or auxiliary air space I is provided with Vanes I2 which are closely associated and designed to assume the position shown in Figure 6. In case a nail or other object penetrates the casing and wall 3 of the tube, and remains in the casing, these vanes would protect the Wall 5 from also being punctured.

Having thus described my invention, what I claim as new is 1. An inner tube for tires comprising a body portion divided into inner and outer circumferentially continuous air space, a valve arranged in a depression in the outer Wall of the outer air space for inlating the same, and a valve for inating the inner air space through its inner wall.

2. An inner tube for tires comprising a body portion divided by a partition into inner and outer circumferential continuous air spaces, the outer wall of the outer air space having an inwardly depressed portion, a Valve in said depressed portion for inlating the outer air space, and a valve carried by the inner wall of the inner air space for inating the same. 3. An inner tube for tires comprising a body portion divided by a partition into inner and outer circumferential continuous air spaces, the

outer air space having an inwardly depressed portion, a valve in said depressed portion for inflating the outer air space, a rubber sleeve surrounding the valve and filling the depressed portion, and a valve carried by the inner wall of the inner air space for inating the same. .CARL G. VRE'IMAN. 

